1. Field of the Invention
The present invention relates in general to fuel injection pumps for internal combustion engines and more particularly to fuel cut solenoid valves for distributor-type or so-called VE-type fuel injection pumps.
2. Description of the Prior Art
In a VE-type fuel injection pump, its working parts are lubricated by fuel to be delivered through the pump. Due to this, broken steel burrs, worn-off iron powder and the like magnetic solid particles may be suspended in the fuel flowing through a fuel passage which is opened or closed by a fuel cut solenoid valve. The fuel cut solenoid valve mainly consists of a cylinder, a solenoid placed around the cylinder, an armature or plunger movable in the cylinder between a first position where it opens the fuel passage and a second position where it closes the fuel passage, and a spring urging the plunger toward the second position. The plunger is moved to the first position when the solenoid is energized.
This kind of fuel cut solenoid valve has a disadvantage that it has a possibility of being disabled to close the fuel passage due to the fact that the suspended solid particles are attracted by the magnetized plunger to gather thereon and may go into the space between the cylinder and the plunger to cause them to seize up. When the plunger becomes fastened to the cylinder, an associated engine cannot be stopped through an ignition key. For the above reason, the prior art fuel cut solenoid valve cannot effect an assured and reliable operation.